The invention relates to a carburetor for an internal combustion engine comprising a mixture forming passage formed in a carburetor housing in which passage a throttle valve and a choke valve are rotatably supported. A lever arrangement is provided that comprises a throttle adjusting lever attached to the throttle shaft and a choke adjusting lever attached to the choke shaft, wherein the throttle valve and the choke valve are adjustable in several operating positions and the lever arrangement assumes corresponding positions.
U.S. Pat. No. 6,550,749 discloses a carburetor for an internal combustion engine of a motor-operated hand-held power tool. The carburetor comprises a throttle valve and a choke valve. For adjusting the throttle valve and the choke valve in interdependent positions as a function of several operating positions such as idle position, cold start position, and warm start position, a switch is provided that is arranged directly on the carburetor and is connected to the choke valve. In this connection, the choke valve and the throttle valve are mechanically coupled with another in such a way that the switch in each of the operating positions assumes a different position. Upon rotation of the switch, an intermediate plate that is supported on the choke shaft is rotated and locks in a predetermined position at the throttle lever.
U.S. Pat. No. 6,000,683 discloses a carburetor for small internal combustion engines that comprises a throttle valve and a choke valve wherein pretensioning means are provided that tension the throttle valve and the choke valve in the direction toward defined positions. A locking device between both valves is provided that secures the two flaps in their starting positions against the action of the pretensioning means. The locking device is releasable by a movement of the throttle valve away from its starting position and comprises a choke lever and a correlated intermediate lever that can be brought into locking engagement with one another. The locking action is released when an operator actuates an accelerator in order to accelerate the engine because the throttle lever is pivoted and releases the intermediate lever.
In the known arrangements release of the locking device is possible only upon actuation of the accelerator while in all other adjusted positions of the operating elements the locking action between throttle valve and intermediate lever remains intact.